The incidence and clinical features of acute kidney injury secondary to ureteral calculi

The utility of flexible and navigable suction access sheath (FANS) in patients undergoing same session flexible ureteroscopy for bilateral renal calculi: a global prospective multicenter analysis by EAU endourology

PURPOSE

To assess the 30-day stone-free rate and peri-operative outcomes of flexible ureteroscopy (FURS) with flexible and navigable suction ureteral access sheaths (FANS) in adults undergoing same-sitting bilateral retrograde intrarenal surgery (SSB-RIRS).

METHODS

Prospectively data of 115 adult patients with bilateral kidney stone disease undergoing SSB-RIRS across 14 global centers between July 2023 and March 2024 were analyzed. Patient demographics, stone characteristics and operative outcomes were recorded. A low-dose non contrast CT scan was performed at 30 days to assess the stone-free rate and clinical outcomes.

RESULTS

Overall bilateral zero residual fragment(ZRF) was 42.6%; unilateral ZRF was 75.7%. Only two patients were noted to have residual fragments > 4 mm. 1.7% experienced Traxer-Thomas grade 1 ureteric injury which was managed with a ureteral stent for four weeks. No pelvicalyceal injury occured. Postoperative mean loin pain score was 1.7 ± 1.0. None had sepsis nor required blood transfusion. 4.3% required readmission within 30 days of surgery. Multivariate analysis indicated longer total operation time correlated with lower odds of achieving a 100% bilateral stone-free (ZRF) (OR 0.978, 95%CI = 0.959-0.994, p = 0.013).

CONCLUSION

To our knowledge, this is the first multicenter study demonstrating the use of FANS in SSB-RIRS can achieve bilateral ZRF with low complication and re-intervention rates. However, prolonged surgical time may negatively impact outcomes. The indications of bilateral renal stones management with FURS can be expanded in appropriate chosen patients.

Renal colic: Streamlining investigations to improve patient outcomes in emergency medicine

OBJECTIVE

In Australian EDs, patients experience long waits for imaging, particularly for presentations such as renal colic. Computed tomography (CT) imaging is the gold-standard for renal stones, although ultrasonography is recommended for young patients and those susceptible to radiation, an approach supported by The Canberra Hospital (TCH) ED guidelines for renal colic. This audit aims to not only assess how well these guidelines are adhered to, but also to discuss possible methods of improving flow through ED and thus patient outcomes.

METHODS

A retrospective audit was conducted using 100 attendances to TCH ED between the dates of 02/04/2022 and 15/06/2022 with the diagnosis of renal colic or calculus. Data were collected on biochemical and radiographic results and patient outcomes with the associations between these datasets statistically analysed.

RESULTS

Blood tests demonstrating abnormal renal function, white cell count and C-reactive protein (CRP) together with haematuria on urine analysis conferred high positive and negative predictive values (83.3% and 100%, respectively) for renal stones. Larger renal stones were associated with higher creatinine and CRP levels and a lower estimated glomerular filtration rate (P = 0.0145, P = 0.0062 and P = 0.0022, respectively).

CONCLUSIONS

We propose that patients with significant clinical and biochemical features of renal stones could be referred to urology earlier to await CT as an inpatient and those without be referred to their general practitioner for outpatient imaging and medical management. This could improve flow through the department and improve patient outcomes through reduced waiting times and radiation burden.

Development and validation of a predictive model for acute kidney injury in patients with ureterolithiasis

OBJECTIVES

This study aims to identify risk factors for acute kidney injury (AKI) in patients with ureterolithiasis and to develop a predictive model for early AKI detection in this population.

METHODS

A retrospective analysis was conducted on data from 1,016 patients with ureterolithiasis who presented to our outpatient emergency department between January 2021 and December 2022. Using multifactorial logistic regression, we identified independent risk factors for AKI and constructed a nomogram to predict AKI risk. The predictive model's efficacy was assessed through the area under the ROC curve, calibration curves, Hosmer-Lemeshow (HL) test, and decision curve analysis (DCA).

RESULTS

AKI was diagnosed in 18.7% of the patients. Independent risk factors identified included age, fever, diabetes, hyperuricemia, bilateral calculi, functional solitary kidney, self-medication, and prehospital delay. The nomogram demonstrated excellent discriminatory capabilities, with AUCs of 0.818 (95% CI, 0.775-0.861) for the modeling set and 0.782 (95% CI, 0.708-0.856) for the validation set. Both calibration curve and HL test results confirmed strong concordance between the model's predictions and actual observations. DCA highlighted the model's significant clinical utility.

CONCLUSIONS

The predictive model developed in this study provides clinicians with a valuable tool for early identification and management of patients at high risk for AKI, thereby potentially enhancing patient outcomes.

Effects of the Surgical Ligation of the Ureter in Different Locations on the Kidney over Time in the Rat Model

Purpose

To evaluate the effects of the surgical ligation of the ureter in different locations on the kidney over time in the rat model.

Methods

A total of 155 rats were enrolled and randomly divided into the case (n = 150) and control (n = 5) groups. The case group included three separate groups (fifty rats in each group) that underwent surgical ureteral ligation at the proximal, middle, and distal ureter. The laboratory tests, and tumor necrosis factor α (TNF-α), were measured in groups. The pathological evaluation for glomerular changes, tubular dilation, interstitial fibrosis, and interstitial infiltration of the inflammatory cells following the obstruction was performed (severity of tubular atrophy categorized too mild (+), moderate (++), and severe (+++)). To compare the continuous variables between the groups and between the measurement times, the analysis of variance (ANOVA) was used.

Results

Our results revealed that the creatinine four weeks after the obstruction was significantly higher in the proximal group obstruction (p value: 0.046). The three groups had no significant differences regarding urine creatinine, serum sodium, and serum TNF (p value: 0.261). Obstruction did not change the glomerular morphology in three intervention groups after six weeks. The commencing of severe tubular atrophy in proximal, middle, and distal ureteral obstruction was at weeks three, four, and six, respectively.

Conclusion

The location of ureteral obstruction is also crucial in deciding to intervene to relieve the complete ureteral obstruction. Severe tubular damage occurs in weeks three, four, and six in proximal, middle, and distal ureteral obstruction, respectively.

A case of post-renal acute kidney injury caused by bilateral ureterolithiasis

Key Clinical Message

Bilateral ureterolithiasis is rare but can cause acute kidney injury (AKI). Clinicians should first examine for post-renal causes of AKI, even if the patient lacks subjective symptoms.

Abstract

This letter describes a case of bilateral ureterolithiasis which presented with post-renal acute kidney injury (AKI) and was successfully treated by bilateral retrograde ureteric stenting. Clinicians should be aware of post-renal AKI caused by bilateral ureterolithiasis when acute worsening of renal function with oliguria is observed.

The Impact of Bilateral Stone Disease on Patients' Disease Progression and Health-Related Quality of Life

Purpose: Patients with recurring kidney stone events can expect significant morbidity and functional impairment. Few studies have evaluated the effect of bilateral kidney stones on disease progression and quality of life. We wanted to determine the association of bilateral stone disease on age of onset, and the impact on number of stone events and individual kidney stone disease-specific health-related quality of life (HRQOL) by analyzing the validated and prospectively collected Wisconsin Stone Quality of Life (WISQOL) database. Materials and Methods: We studied 2906 stone patients from 16 centers in North America after having completed the WISQOL questionnaire from 2014 to 2019. Kidney stone formers were assessed if kidney stones were bilateral or unilateral on imaging. Analysis with a chi-square test compared categorical variables. Bilateral kidney stone disease and its impact on HRQOL were evaluated through a multivariable linear regression model. Results: Of 2906 kidney stone formers, 1340 had unilateral kidney stones and 1566 had bilateral kidney stones. We observed more frequently that patients with bilateral stones had an increased number of depression/anxiety symptoms, renal tubular acidosis, and rheumatoid arthritis (all p < 0.05). Patients with bilateral stones had a younger mean (standard deviation [SD]) age of kidney stone disease onset (37.2 ± 15.8 vs 46.4 ± 15.9 years of age, p < 0.001). Bilateral kidney stone formers had a higher mean (SD) number of stone events (11.3 ± 21.8) than unilateral kidney stone formers (3.0 ± 5.1) (p < 0.001). Within our multivariable analysis, we found that HRQOL was negatively affected by the presence of bilateral stones for kidney stone patients (β = -11.2 [confidence interval: -19.5 to -3.0] points, p < 0.05). Conclusions: Bilateral kidney stone formers had a younger age of kidney stone disease onset and a higher number of stone events compared with unilateral kidney stone disease formers. The presence of bilateral kidney stone disease negatively impacted HRQOL.

Impact of acute kidney injury on long-term adverse outcomes in obstructive uropathy

Obstructive uropathy is known to be associated with acute kidney injury (AKI). This study aimed to investigate the etiologies, clinical characteristics, consequences and also assess the impact of AKI on long-term outcomes. This multicenter, retrospective study of 1683 patients with obstructive uropathy who underwent percutaneous nephrostomy (PCN) analyzed clinical characteristics, outcomes including progression to end-stage kidney disease (ESKD), overall mortality, and the impact of AKI on long-term outcomes. Obstructive uropathy in adults was most commonly caused by malignancy, urolithiasis, and other causes. AKI was present in 78% of the patients and was independently associated with preexisting chronic kidney disease (CKD). Short-term recovery was achieved in 56.78% after the relief of obstruction. ESKD progression rate was 4.4% in urolithiasis and 6.8% in other causes and older age, preexisting CKD, and stage 3 AKI were independent factors of progression. The mortality rate (34%) was highly attributed to malignant obstruction (52%) stage 3 AKI was also an independent predictor of mortality in non-malignant obstruction. AKI is a frequent complication of adult obstructive uropathy. AKI negatively affects long-term kidney outcomes and survival in non-malignant obstructions. A better understanding of the epidemiology and prognostic factors is needed for adult obstructive uropathy.

Ureteral stone with hydronephrosis and urolithiasis alone are risk factors for acute kidney injury in patients with urinary tract infection

To identify whether urolithiasis with or without hydronephrosis has an impact on acute kidney injury (AKI) in patients with urinary tract infection (UTI). This study aimed to identify whether urolithiasis with or without hydronephrosis has an impact on AKI in patients with UTI. This retrospective study enrolled hospitalized UTI patients who underwent imaging in an acute care setting from January 2006 to April 2019. Of the 1113 participants enrolled, 191 (17.2%) had urolithiasis and 76 (6.8%) had ureteral stone complicated with hydronephrosis. Multivariate logistic regression analysis showed that in UTI patients with urolithiasis, the presence of ureteral stone with concomitant hydronephrosis was an independent risk factor for AKI (odds ratio [OR] 2.299, 95% confidence interval [CI] 1.112–4.755, P = 0.025). In addition, urolithiasis was associated with an increased risk for AKI (OR 2.451, 95% CI 1.369–4.389, P = 0.003) in UTI patients without hydronephrosis. The presence of ureteral stone with hydronephrosis increases the risk for AKI of UTI patients with urolithiasis, and urolithiasis remains a risk factor of AKI in UTI patients without hydronephrosis.

Incidence and risk factors of venous thromboembolism after percutaneous nephrolithotomy: a single-center experience

PURPOSE

To determine the incidence and risk factors of the venous thromboembolism (VTE) in patients undergoing percutaneous nephrolithotomy (PCNL).

METHODS

We retrospectively reviewed the records of 896 consecutive cases receiving PCNL between July 2018 and August 2020 in our institution. Univariate analysis was performed to identify the risk factors of VTE, and multivariate logistic regression analysis was further performed to determine the independent risk factors. Furthermore, the corresponding nomogram was conducted to establish a predicted model for VTE.

RESULTS

The overall incidence of VTE was 2.8%. The multivariate logistic regression analysis showed that discontinued anticoagulant or antiplatelet therapies (OR 4.505, 95% CI 1.410-14.401), increased postoperative 12-h D-dimer (OR 11.162, 95% CI 2.370-52.574), hydronephrosis (OR 3.303, 95% CI 1.303-8.375), higher Caprini risk assessment model (RAM) score (OR 3.233, 95% CI 1.207-8.659) and postoperative sepsis or septic shock (OR 3.784, 95% CI 1.163-12.306) were independent risk factors of VTE following PCNL. Moreover, the area under the curve of postoperative 12-h D-dimer, hydronephrosis and Caprini RAM score was 0.826, 0.621 and 0.660, respectively. Based on the identified independent risk factors, the well-calibrated nomogram showed a moderate discriminative ability with concordance index 0.731.

CONCLUSIONS

2.8% of patients developed VTE following PCNL. Regarding those patients who have independent risk factors in this study, due attention should be paid to the effective thromboprophylaxis and the early detection of VTE.

Are endourological procedures for nephrolithiasis treatment associated with renal injury? A review of potential mechanisms and novel diagnostic indexes

Nephrolithiasis is one of the most common urological conditions with a huge socio-economic impact. About 50% of recurrent stone-formers have just one lifetime recurrence and >10% of patients present with a high recurrent disease requiring subsequent and sometimes multiple surgical interventions. The advent of new technology has made endourological procedures the pinnacle of stone treatment, including procedures like percutaneous nephrolithotomy (PCNL), retrograde intrarenal surgery and miniaturized PCNL procedures. Researchers have primarily focused on comparisons with respect to stone-free rates, procedure parameters and post-operative complications. However, the effect of these three procedures on renal function or indexes of renal injury has not been sufficiently examined. This was only reported in a few studies as a secondary objective with the use of common and not the appropriate and detailed renal parameters. This review presents current literature regarding the use of novel and highly predictive biomarkers for diagnosing acute kidney injury, discusses potential mechanisms through which endourological procedures for renal stone treatment may affect renal function and proposes areas with open questions where future research efforts in the field should focus.

Acute Kidney Injury Associated With Urinary Stone Disease in Children and Young Adults Presenting to a Pediatric Emergency Department

Background: Acute kidney injury (AKI) due to urinary stone disease (USD) is rare in adults; AKI rates in children with USD may be higher, and emerging data links stones to chronic kidney disease (CKD) development in adults. Methods: This study is a retrospective analysis of USD patients at a single pediatric hospital system's emergency department (ED). Patients were initially identified by USD ICD codes; USD was then confirmed by imaging or physician documentation; patients had to have baseline creatinine (Cr) and Cr in the ED for comparison to be included. AKI was defined by Kidney Disease: Improving Global Outcomes (KDIGO), Acute Kidney Injury Network (AKIN), and Pediatric Risk, Injury, Failure, Loss, End Stage (pRIFLE). Results: Of the 589 total visits, 264/589 (45%) had data to evaluate for AKI, 23% were AKI(+) and 77% were AKI(-). pRIFLE was most common (82%) and 18% were only positive by AKIN/KDIGO. AKI(+) were more likely to be younger (16.7 vs. 17.4 years, p = 0.046) and more likely to present with vomiting {odds ratio [OR] [95% confidence interval (CI)]: 2.4 [1.4-4.3], p = 0.002}; also, the proportion of AKI(+) was significantly higher in <18 vs. ≥18 years [26.9 vs. 15.5%, p = 0.032, OR (95% CI): 2.0 (1.1-3.9)]. Urinary tract infection (UTI) and obstruction rates were similar between groups. AKI(+) patients had a significant OR <1 suggesting less risk of receiving non-steroidal anti-inflammatory drugs (NSAIDs); however, 51% of them did receive NSAIDs during their ED encounter. AKI(+) patients were more likely to require admission to the hospital (53 vs. 32%, p = 0.001). Conclusion: We have demonstrated a novel association between USD-induced renal colic and AKI in a group of young adults and children. AKI(+) patients were younger and were more likely to present with vomiting. AKI(+) patients did not have higher rates of obstruction or UTI, and 51% of AKI(+) received NSAIDs.

Effects on renal outcome of concomitant acute pyelonephritis, acute kidney injury and obstruction duration in obstructive uropathy by urolithiasis: a retrospective cohort study

OBJECTIVE

Obstruction release from urolithiasis can be delayed with a lack of suggested time for preventing the deterioration of renal function. The objective of this study was to investigate the effect of obstruction duration, concomitant acute kidney injury (AKI) or acute pyelonephritis (APN) during the obstruction on the prognosis of renal function.

DESIGN

Retrospective cohort study.

SETTING AND PARTICIPANTS

1607 patients from a urolithiasis-related obstructive uropathy cohort, between January 2005 and December 2015.

OUTCOME MEASURES

Estimated glomerular filtration rate (eGFR) decrease ≥30% and/or end-stage renal disease (ESRD), and eGFR decrease ≥50% and/or ESRD, according to obstruction duration, AKI and APN accompanied by obstructive uropathy.

RESULTS

When the prognosis was divided by obstruction duration quartile, the longer the obstruction duration the higher the probability of eGFR reduction >50% (p=0.02). In patients with concomitant APN or severe AKI during hospitalisation with obstructive uropathy, an eGFR decrease of >30% and >50% occurred more frequently, compared with others (p<0.001). When we adjusted for sex, age, hypertension, diabetes mellitus, APN, AKI grades and obstruction release >7 days for multivariate analysis, we found that concomitant APN (HR 3.495, 95% CI 1.942 to 6.289, p<0.001), concomitant AKI (HR 3.284, 95% CI 1.354 to 7.965, p=0.009 for AKI stage II; HR 6.425, 95% CI 2.599 to 15.881, p<0.001 for AKI stage III) and an obstruction duration >7 days (HR 1.854, 95% CI 1.095 to 3.140, p=0.001) were independently associated with an eGFR decrease >50%. Tree analysis also showed that AKI grade 3, APN and an obstruction duration >7 days were the most important factors affecting renal outcome.

CONCLUSIONS

In patients with urolithiasis-related obstructive uropathy, concomitant APN was strongly associated with deterioration of renal function after obstruction release. The elapsed time to release the obstruction also affected renal function.

To study the incidence and preintervention factors associated with acute kidney injury in patients diagnosed with ureteric calculi

Aims and Objectives:

The study aims to evaluate the incidence and factors associated with acute kidney injury (AKI) among patients presenting with ureteric calculi. We also intend to study the impact of time delay since first symptom to presentation to our hospital among patients with ureteric calculi and its influence on AKI.

Material and Method:

The study is a prospective observational study and included all symptomatic ureteric calculi patients. AKI was defined as per the KDIGO guidelines. All the patients diagnosed with ureteric calculi were grouped into those having an episode of AKI and those without an episode on AKI.

Results:

The incidence of AKI in our study was 14.63% (18 patients) among 123 patients of ureteric calculi. Average time delay from time of diagnosis to presentation among patients with AKI was 31.7±6.2 days (mean ± S.D) as compared to 19.5±5.7 (mean ± S.D) days among all cases. Factors which were significantly associated with AKI in patients with ureteric calculi include time delay, diabetes mellitus, bilateral ureteric calculi, stone size greater than 10 mm, solitary functioning kidney and urine culture showing gram negative growth. Fifty percent of the AKI group eventual required nephrectomy of one renal unit.

Conclusion:

This study will help us streamline our resources predominantly towards those patients who present with factors associated with increased risk of AKI. As the time delay to presentation in patients with AKI with ureteric calculi is significantly higher, it is imperative to counsel patients with stone disease.

A radiologist’s approach to CT KUB for the urologist

In this article we review the computed tomography imaging features of renal and ureteric calculi, the secondary signs of renal tract calculi and their possible complications. Most calculi appear as high-density foci due to their composition, whereas other signs that may be appreciated include the soft-tissue rim sign in the ureter, upstream renal tract dilation and peri-ureteric or peri-renal stranding. The most accurate means of measuring a calculus is in the coronal plane on bone windows. We also provide a systematic approach to interrogating computed tomography of the kidneys, ureter and bladder for the urologist, with examples of other conditions that may present as renal colic and are apparent on computed tomography.

Level of evidence: Not applicable as no original research is being proffered.

Study of non-contrast helical computed tomography in evaluating holmium laser lithotripsy for urinary calculus

The present study aimed to investigate the correlation between the parameters of non-contrast helical computed tomography (NCHCT) and the total energy of holmium laser lithotripsy, and establish a correlative mathematical model. From March 2016 to February 2017, 120 patients with a single urinary calculus were examined by NCHCT prior to holmium laser lithotripsy. The calculus location was confirmed, the CT value was measured and the volume of the calculus in the established three-dimensional reconstruction model was calculated. The total energy of lithotripsy (TEL) was recorded post-operatively. A significant difference in the TEL between renal calculi and ureteral calculi was identified (P<0.001) and a high and significant correlation between the volume of the calculus and the TEL was determined (Spearman r=0.827, P<0.001). A moderate correlation was identified between the CT value of the calculus and the TEL (Spearman r=0.468, P<0.001). Multivariate linear regression analysis revealed that the location, the volume and the CT value of the calculus were independently associated with the TEL (F=288.858, adjusted R²=0.879, P<0.01). A mathematical model correlating the parameters of NCHCT with the TEL was established, which may provide a foundation to guide the use of energy in holmium laser lithotripsy, and it was possible to estimate the TEL by the location, the volume and the CT value of the calculus.

Development and validation of a risk-prediction nomogram for patients with ureteral calculi associated with urosepsis: A retrospective analysis

Objectives

To develop and validate an individualized nomogram to predict probability of patients with ureteral calculi developing into urosepsis.

Methods

The clinical data of 747 patients with ureteral calculi who were admitted from June 2013 to December 2015 in Affiliated Nanhai Hospital of Southern Medical University were selected and included in the development group, while 317 ureteral calculi patients who were admitted from January 2016 to December 2016 were included in the validation group. The independent risk factors of ureteral calculi associated with urosepsis were screened using univariate and multivariate logistic regression analyses. The corresponding nomogram prediction model was drawn according to the regression coefficients. The area under the receiver operating characteristic curves and the GiViTI calibration belts were used to estimate the discrimination and calibration of the prediction model, respectively.

Results

Multivariate logistic regression analysis showed that the five risk factors of gender, mean computed tomography(CT) attenuation value of hydronephrosis, functional solitary kidney, urine white blood cell(WBC) count and urine nitrite were independent risk factors of ureteral calculi associated with urosepsis. The areas under the receiver operating characteristic curve of the development group and validation group were 0.913 and 0.874 respectively, suggesting that the new prediction model had good discrimination capacity. P-values of the GiViTI calibration test of the two groups were 0.247 and 0.176 respectively, and the 95% CIs of GiViTI calibration belt in both groups did not cross the diagonal bisector line. Therefore the predicted probability of the model was consistent with the actual probability which suggested that the calibration of the prediction model in both groups were perfect and prediction model had strong concordance performance.

Conclusion

The individualized prediction model for patients with ureteral calculi can facilitate improved screening and early identification of patients having higher risk of urosepsis.

Acute kidney injury in Ureteric Stones:Single centre short term analysis

OBJECTIVE

To analyze acute kidney injury (AKI) frequency, risk factors and outcome in ureteric stone patients.

METHODS

This is an observational retrospective study performed in a single tertiary care centre in Abu Dhabi from October 2014 till August 2015. Convenient sampling was done on 152 consecutive patients who underwent decompression surgery (Ureterorenoscopy LASER Lithotripsy and DJ Stenting) for ureteric stones. Serum Creatinine was used to calculate creatinine clearance by cock croft Gault formula in all patients before and after procedure. Analysis was done on SPSS version 17.

RESULTS

Out of 152 patients who under went decompression surgical procedure for ureteric stones AKI was seen in 49(32.2%). Patients with AKI were found to be more higher age, increasedweight, bilateral stones, lower ureteric stones and with co morbidities in comparison to those who were without acute kidney injury. Patients developing AKI, 89.7% recovered either partially(20.4 %) or completely (69.3%).

CONCLUSION

AKI is seen more in ureteric stone patients with older age, increased weight, bilateral stones, lower ureteric stones and with co morbidities. Recovery is good when obstruction is relieved.

The profile of patients with obstructive uropathy in Cameroon: case of the Douala General Hospital

Introduction

Obstructive uropathy can lead to irreversible kidney damage. The etiology largely determined by the patient's age can be benign or malignant. This study aimed at determining the profile and outcome of patients with obstructive uropathy in Cameroon.

Methods

A cross sectional study carried out in the urology unit of the Douala General Hospital, including patients with a diagnosis of obstructive uropathy seen from January 2004 to December 2013. Clinical profile, treatment and outcome data were obtained from patients records.

Results

Of the 229 patients included 69% were men, mean age 50 ±18 years. Associated comorbidities were hypertension, diabetes, and HIV. Mean haemoglobin 8,40±2,4g/dl, mean GFR 10,3 ±10ml/min, 94 (41%) patients needed emergency dialysis. Symptoms at presentation: asthenia (57%), anorexia (55%), loin pain (37%), vomiting (28%), oedema (20%), and anuria (15%). Urinary tract infection was present in 33 patients. Main aetiologies of obstruction: urolithiasis (35%), begnin prostatic hypertrophy (27%), prostatic cancer (12%), cervical cancer (16%), and congenital malformations (5%). Drainage was effective in 102 (45%) patients, 63 (28%) recovered completely, 91 (41%) were loss to follow up, 49 (22%) died and more women (p = 0.02). Mortality was associated with prostatic cancer (p = 0.000), cervical cancer (p = 0.004) and radiotherapy (p = 0.03).

Conclusion

Patients with obstructive uropathy presented with significant impaired renal function. Main causes were urinary stones, prostatic hypertrophy, prostatic and cervical cancers. Renal recovery was poor, loss to follow up and mortality high. Specific strategies to target improvement in renal recovery and patient's survival are needed in this patient's group.

Do kidney stone formers have a kidney disease?

Nephrolithiasis is a highly prevalent disorder affecting approximately one in eleven people and is associated with multiple complications including hypertension, cardiovascular disease, and chronic kidney disease. Significant epidemiologic associations with chronic kidney disease and ESRD have been noted and are reviewed herein, but debate persists in the literature as to whether kidney stone formation is a pathogenic process contributing to kidney disease. Corroborating evidence supporting the presence of kidney disease in stone formers includes the variability of renal function by stone type, the positive association of stone size with renal dysfunction, the presence of markers of renal injury in the urine of even asymptomatic stone formers, and direct evidence of renal tissue injury on histopathology. Proposed pathogenic mechanisms include recurrent obstruction and comorbid conditions such as recurrent urinary tract infections and structural abnormalities. Recent work evaluating the renal histopathology of different groups of stone formers adds further granularity, suggesting variability in mechanisms of renal injury by stone type and confirming the pathogenic effects of crystal formation. Genetic abnormalities leading to stone formation including cystinuria and primary hyperoxaluria, among others, contribute to the burden of disease in the stone-forming population.

Novel biomarkers of acute kidney injury: Evaluation and evidence in urologic surgery

Patients undergoing urologic surgery are at risk of acute kidney injury (AKI) and consequently long-term deterioration in renal function. AKI is further associated with significantly higher odds of perioperative complications, prolonged hospital stay, higher mortality and costs. Therefore, better awareness and detection of AKI, as well as identification of AKI determinants in the urological surgery setting is warranted to pre-empt and mitigate further deterioration of renal function in patients at special risk. New consensus criteria provide precise definitions of diagnosis and description of the severity of AKI. However, they rely on serum creatinine (SCr), which is known to be an inaccurate marker of early changes in renal function. Therefore, several new urinary and serum biomarkers promise to address the gap associated with the use of SCr. Novel biomarkers may complement SCr measurement or most likely improve the diagnostic accuracy of AKI when used in combinations. However, novel biomarkers have to prove their clinical applicability, accuracy, and cost effectiveness prior to implementation into clinical practice. Most preferably, novel biomarkers should help to positively improve a patient’s long-term renal functional outcomes. The purpose of this review is to discuss currently available biomarkers and to review their clinical evidence within urologic surgery settings.

Acute and chronic kidney injury in nephrolithiasis

PURPOSE OF REVIEW

Nephrolithiasis is a common systemic disease associated with both acute kidney injury (AKI) and chronic kidney disease (CKD). The purpose of this review is to discuss recent publications regarding nephrolithiasis-associated kidney damage, with an emphasis on AKI.

RECENT FINDINGS

Nephrolithiasis is not a common cause of adult AKI (1-2% of cases), although it may be a more important factor in young children (up to 30%). The primary mechanism of nephrolithiasis-associated AKI is obstructive nephropathy, and factors on presentation with obstructive uropathy predict the likelihood of long-term renal recovery. Crystalline nephropathy is another potential pathway in certain circumstances that is often associated with a worse outcome. Recent studies have elucidated additional pathways whereby calcium oxalate crystals can cause acute injury, implicating innate immunity and intracellular inflammasome pathways. Several large cohort studies have demonstrated an independent association of nephrolithiasis with CKD and end-stage renal disease, although the effect size is modest. Urologic comorbidities, urinary infection, and shared underlying risk factors (e.g., diabetes, hypertension) all impact nephrolithiasis-associated CKD risk.

SUMMARY

Obstructive nephropathy and crystalline nephropathy both contribute to nephrolithiasis-associated AKI, although the latter appears to have a worse prognosis. Nephrolithiasis is an independent, albeit small, risk factor for CKD. Further study is needed to clarify the incidence and mechanisms of nephrolithiasis-associated AKI, and the relationship between nephrolithiasis-associated AKI and CKD.

Bilateral stones as a cause of acute renal failure in the emergency department

BACKGROUND

Acute renal failure (ARF) due to obstructive uropathy is a urological emergency. The standard radiological investigations in the emergency setting include X-ray, ultrasonography and computed tomography. But occasionally the cause of obstruction may be elusive.

METHODS

We present a case of obstructive uropathy due to bilateral stones presenting as acute renal failure. The patient underwent successful shock wave lithotripsy (SWL) for dissolution of calculi.

RESULTS

The patient was successfully treated, and reported asymptomatic in a follow-up.

CONCLUSION

Close collaboration between nephrological, urological, and radiological services is required.

Acute kidney injury in urology patients: incidence, causes and outcomes

BACKGROUND

Acute kidney injury (AKI) is common in hospitalised patients and is associated with high mortality rates. However, the epidemiology of AKI in urology patients may differ due to a higher proportion of post-renal causes and surgical procedures that result in the intentional removal of renal parenchyma.

OBJECTIVES

We performed a study to examine the incidence, aetiology and outcomes of AKI in a urological population.

PATIENTS AND METHODS

We performed a single-centre observational study including all hospitalised patients who sustained AKI within the Urology Department over an 18 month period. Patients with AKI were prospectively identified by a hospital-wide, electronic AKI reporting system that also allows demographic, hospital admission and co-morbidity data collection. Data regarding aetiology of AKI and details of surgical procedures were added retrospectively by manual case-note search.

RESULTS

587 episodes of AKI occurred in 410 urology patients, giving an overall incidence of 6.7%. 137 (33.4%) were elective cases of whom 58 had undergone nephrectomy (radical and partial). Urinary obstruction and sepsis were the predominant causes of AKI in the 273 patients (66.6%) admitted as an emergency. Overall 30-day mortality was 7.8%; increasing severity of AKI was associated with mortality (4.8% in stage 1, 9.1% in stage 2, 14.9% in stage 3, P = 0.007). At time of discharge, only 57.7% of patients had recovered pre-morbid renal function. The observational nature of this study is a limitation, preventing determination of causality of associations.

CONCLUSIONS

AKI is common in urology patients. The underlying aetiologies of AKI in this group may explain a lower overall mortality, although increasing AKI severity remains a marker of patients at higher risk of poor outcomes. The low rate of renal recovery suggests that urology patients who sustain AKI are exposed to a significant risk of CKD and its attendant consequences for long term health.